Firmware update failed
Vaillant vSMART Firmware Update Interruption

vSMART app reports 'Firmware update failed' or the thermostat/gateway reboots repeatedly during an update.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Loss of internet during update, power interruption to vSMART gateway, insufficient Wi‑Fi signal strength, corrupted firmware package from server

How to Fix / Troubleshooting

Safety: Do not repeatedly power‑cycle the device during an update unless instructed; this can brick the unit.

Steps to recover:

  • Stabilize network: Move the gateway closer to the router or connect it via Ethernet if possible. Ensure the internet connection is stable.
  • Ensure stable power: Plug the gateway into a reliable socket, avoiding loose adapters or extension leads that may cut power.
  • Retry update: From the Vaillant app, check for updates again and retry. Allow sufficient time for the process to complete without interruption.
  • Reboot once: If the device is stuck, perform a single controlled reboot (unplug for 30 seconds, then reconnect) and then attempt the update again.

If the gateway or thermostat will not boot properly after a failed update (no LEDs, no display, or stuck on logo), contact Vaillant support. The device may require service or replacement.

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Repair Difficulty

Medium 3/5

Required Part

vSMART Internet Gateway
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